The correct answer is B. RangeValidator.
A RangeValidator is a server control that validates that a value is within a specified range of values. It is used to verify that an entry is within the specified minimum and maximum values.
The CompareValidator is used to verify that the value of one control is equal to the value of another control.
The RequiredFieldValidator is used to verify that a control has a value.
The ValidationSummary is a server control that displays the results of all validation controls on a page.
Here is a sample code for using a RangeValidator:
<asp:RangeValidator ID="RangeValidator1" ControlToValidate="TextBox1" MinimumValue="1" MaximumValue="10" />
In this example, the RangeValidator will validate that the value of the TextBox1 control is between 1 and 10.